Solution: 1. #1st naive idea is to use inorder traversal, because of the characteristics of binary search tree, when the kth number is visited, #it is the kth smallest value time complexity o(k), worst time complexity o(n) (1). use recursive way 1defbfsInorderRecursive(node, ansLst)...
publicintkthSmallest(TreeNode root,intk) { Stack<TreeNode> stack =newStack<TreeNode>(); TreeNode p = root; while(p!=null){ stack.push(p); p=p.left; } inti=0; while(!stack.isEmpty()){ TreeNode t = stack.pop(); i++; if(i==k) returnt.val; TreeNode r = t.right; while...
LeetCode Kth Smallest Element in a BST(数据结构) 题意: 寻找一棵BST中的第k小的数。 思路: 递归比较方便。 1 /** 2 * Definition for a binary tree node. 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL...
方法一: 1classSolution {2public:3intkthSmallest(TreeNode* root,intk) {4stack<TreeNode*>nodeStack;5if(root == NULL)return-1;6while(true){7while(root){8nodeStack.push(root);9root = root->left;10}11TreeNode* node =nodeStack.top(); nodeStack.pop();12if(k ==1)returnnode->val;1...
Tree - 230. Kth Smallest Element in a BST 230. Kth Smallest Element in a BST Given a binary search tree, write a functionkthSmallestto find thekth smallest element in it. **Note: ** You may assume k is always valid, 1 ≤ k ≤ BST's total elements....
Given a binary search tree, write a functionkthSmallestto find the kth smallest element in it. Note: You may assume k is always valid, 1 ≤ k ≤ BST's total elements. Follow up: What if the BST is modified (insert/delete operations) often and you need to find the kth smallest frequ...